Stylus head mounting



Aug. 18, 1942.

F. RIEBER STYLUS HEAD MOUNTING Fil ed Aug. 2, 1941 INVENTOR B Fm kick/-Y 6 ATTORNEY" Patented Apr. 18, 1942 UNITED STATES -PATENT OFFICE smusHEAD Momma Frank 'Bieber, Lbs Angele s, ,CaliL, allignor to Memovox,tlon of Ohio lnc., Beverly Hills, Call! a corpora- J Application August2, 1941, Serial no. 405,178 .11 chums. (01.2751)? In commerciahrecording machines, such as used formaking records of dictation,aircraft communications, and the like, it is frequently necessary toplayback or reproduce some or all of the material just recorded. Forthis purpose, such machines are often equipped with a single apparentthat even a very 'slightmovement will be suilicient to injure, thegroove, and the movehead carrying a record engaging stylus, which byappropriate switching of the amplifier connectionscan becaused'optionally to act .as a recorder in response to modulationsreceived from a microphone or to operate as a reproducer, to

affect a'speaker in response to undulations of a record.

Whenmaking, a record, the stylus forms the record groove and hence mustbe positively advanced across the record surface in exact accord ancewith the movement of the feed mechanism.

a In reproducing a record, however, while it is still desirable topositively advance the stylus over the record, a limited freedom ofmovement between the feed mechanism and the stylus is re- 'quired, inorder that thestylus be permitted 'accurately to follow the recordgrooves; Such freedom of movement 'is' conveniently termed flateralcompliance. l

Further, it is obviously necessary that the stylus exert a considerablepressure on the recment may easily be sumcient to cause the stylus tocross from one groove to the adjoining groove and permanently injure therecord.

It is accordingly another object of the invention to provide mechanismof the character describedwhich will lock the head against lateralcompliance'without causing any lateral movef ment of the head.

It is still another object of this invention to provide mechanism'of thecharacter described of increased simplicity and 'ease of operation. Thisinvention possesses many other advantages, and has other objects whichmay be made more easily apparent from a consideration of one embodimentof the invention. For this purpose there is shown a form in the drawingaccompanying and mm; part of the present specisense, since the-scopeofthis invention 0rd when cutting or' embossing a record; but

. when playing .back a previouslymade record, the

pressure should be quite light.

It is an'object of this invention to provide an improved mechanism forchanging the condition of a stylus head to prevent or to allow suchfree-' dom or lateral compliance.

, It, is another object of this inventionto-provide improved mechanismfor. altering the pres sure exerted by the stylus on the record.

I Devices for locking such heads against lateral compliance usuallyinvolve some sort ofa con- 'straint against motion of'the headabout anaxis;

as for example a'centering arrangement, such as a pin seating in aV-notch. 'Ihestylus is correspondingly forced into a defln'itepositionwith respect to the feed mechanism, and is maintained in that positionwhile .the constraint is effective. Nevertheless, after the recordgroove is provided with the undulations forming the record, the positionof the stylus under the constraint isapt to 'be slightly incorrectforthereproducing position. This may be due to a slight eccentricity ofthe groove, or other causes. Therefore the operation of locking willalmost certainly cause a 'slight claims.

jll'igs. 2, 3 and 4 are sectional viewsas taken on 1 the correspondinglynumbered planes of 'Fig, l.

' A phonograph turntable is indicated by I, and

-may be of anywellknown or preferred type,

serving to carry a record 2. Although a disc 'form of record is shown,the mechanism about to be described is equally applicable toacylindrical record, or a recordin the form of a loop.

The stylus 3 which cooperates with. the record surface is shown, forexample, as carried by an electrical type stylus head 4. This head is ofa type which will function either as a recorder or a reproducer,suitable circuits being provided by means of which it maybe optionallyconnected .to a r a microphone or a speaker through a suitable Such'.heads and circuits are well amplifier. known to those skilled in theart, and accordingly will not be' further described.

. The head 4 is mounted on a short arm 5 which" is attached to acarriage i by a pivoted connection I. Carriage 6 maybe supportedformovement parallel with the surface of record 2 by spaced parallelrods 8. suitably supported as on lateral movement of the stylus on therecord.

' Since record grooves are commonly spaced in the neighborhood of150per-inc'h, it will be readily the frame of the phonograph (notshown). The carriage 6 is caused to travel along rods 8 and thustraverse the record by means of a feed screw turntable I.

9, engaged by a frictional nut l mounted on carriage 6 by a resilientarm II.

The feed screw 9 is rotated at a definite angu-- shown). .Thus thestylus follows a spiral track extending between the periphery of therecord and a point near the center of the record.

The pivoted connection I (shown most clearly in Fig. 3) includes aclevis l3 with a shank l4 supported in a suitable bore in a boss IS onthe carriage 6 We washer l6 and a pin I! on top of lar velocity withregard to the angular motion of the turntable by appropriate mechanism(notthe boss. Accordingly clevis I3 is rotatable about an axis l8 normalto the surface of the record 2. In the legs I! of clevis l3 are alinedpivot points 20 engaging opposite sides of arms 5. The axis 2| of pivotsis substantially parallel to the record surface. Pivots 20 mayconveniently be hardened cone pointed screws. 1

When head 4 isfunctioning as a reproducer, the stylus 3 must follow thespiral groove 'on the record surface. Since the position of this groovemay not at all times coincide with the position .of the stylus asdetermined by movement of car'- riage- 6 in response to feed screw 9,the head 4 must have some freedom-of motion laterally of the record withrespect to the carriage. so called lateral compliance is provided byslight angular movement of head 4, arm 5 and clevis.

l3 about axis l8. Similarly stylus 3 must be free to follow. undulationsof the record surface in a generally vertical direction; such movementis permitted head 4 and arm 5 with respect to clevis l3 and carriage 6about axis 2|. Stylus 3 is thus enabled to follow all deviations of therecord groove without undue wear or damage to the groove. At the sametime, the advance of carriage 6 carrying thehead 4 relieves this grooveof the necessity of moving any substantial mass.

is secured on ar extending away from the head and beyond the axis 2|.This finger 23 is without effect when the head is reproducing other thanto restrict the-lateral, freedom of movement to a reasonable amount.'Thus, pins 24 and 25 extend downwardly from carriage 6, a short distanceon opposite sides respectively of finger 23. These pins by engaging oneside or the other of finger 23 serve to limit the. movement of thefinger, arm 5 and head 4, when for example the head 4 is lifted manuallyabout axis 2| to remove and replace a record on the ,A plunger 26 isslidably mounted for vertical movement on carriage 6 in boss 2'! andcarries an abutment 28 at its lower end, adapted to engage the free end29 of finger 23 when the plunger 26 is raised. When the plunger 26 is inits lower position abutment 28 is entirely clear of finger 23. When theplunger 26 is raised, abutment 28 engages end 29 of finger 23, andflexes the finger 23 until end 29 engages a friction pad 36 of fibre orfelt or the like on carriage '6 as shown in broken lines, Fig. 1.

Means are provided for causing plunger 26'to urge the extremity 29 offinger 23 against pad 30 with sufiicient force to' maintain arm 5- andconnected parts against movement about -axis IS in response to forcesincident to recording.

Thus head 4 ismoved accurately by carriage 6, stylus 3 forming therecord groove. At the same time, the upward flexing of finger 23 exertsa downward force on head 4, and augments the pressure exerted by stylus3 on the record.

and finger 23 which contact are plane, thus the force urging themtogether has, no tendency whatever to move the finger, arm- 5 and head 4laterally of the record, about-axis l8,

One mechanism for moving plunger 26 and spring finger 23 upwardly andmaintaining the latter in engagement with pad 30 may compriseelectromagnetic means.. Thus, plunger 26 carries f a core 3|, ofmagnetic material, on its upper end. Core 3| cooperates with a solenoid,diagrammatically shown at 32, adapted to be ener-- gized from anyconvenient source, such as battery 3'3, controlled by a manuallyoperable switch 34.

When it is desired to use stylus head 4 for reproducing, switch34 isallowed to remain open,

deenergizing .coil 32. Plunger 26 will then' remain in its lowerposition, without affecting spring finger 23. When it is desired torecord,

switch 34 is closed, energizing coil 32 which causes plunger 26 toriseto its upper position,

- flexing spring finger 23- and urging it against pad 30. This-locks thehead 4 against lateral to the-head 4 when-the plunger 26 is allowed to Iing conditions of thehead 4, a spring finger 23 compliance and increasesthe pressure of stylus 3 on the record. It is to beunderstood that onoccasions when it is necessary to lift the .stylus out of" engagementwith the record, upon re- 3 placing it on the record, the head should bepositioned so that finger 23 is approximately intermediate the pins 24,and 25.

In order to prevent. any slight blow or shock drop to .its lowerposition, a resilient ring. or

- bumper 35 formed of rubber for example may be provided on boss 21 toact as a stop for'core 3|.

What is claimed is:

I 1. A stylus head, arranged to cooperate with a record, a carriagearranged to move the head transversely of the record, means forming apivotal support for the'head on the carriage,-'said support permittingmovement of .the head to or from the record surface, a spring fingerattached to the head and having a'free end, a plunger carried by theca-rriageand optionally movable with respect thereto, said plunger beingadapted upon movement to engage the free end of the spring finger,flexing the spring and urging the head about said pivotal support.

2. A stylus head, arranged to cooperate with a record, a carriagearranged to move the. head.

transversely of the record, means, forming a pivotal support for thehead on the carriage, said support having a pair of pivotal connections,said connections having axes respectively parallel with and transverseto, the record surface, means for urging said support toward therecordsurface comprising a spring finger on said head; means on thecarriage for optionally flexing the finger, and means on the carriageadapted to be v 3. In a stylus head mounting, a carriage arranged tomove transversely of therecord surface, means connecting the head formovement It willbe noted that the surfaces ofpad 30 1 with the carriagecomprising means whereby the head may have limited lateral movement withrespect to the carriage, as well as movement to and from the recordsurface, means to secure the head against lateral movement'with respectto the carriage comprising a resilient member attached to the head, afriction padon the carriage, and means to flex said member and urge itinto engagement with said pad, said member being so arranged that theflexing urges the head toward-the record surface.

4. In a stylus head mounting, a carriage arranged to move transverselyof the record surface, means for supporting the head on the carriageincluding a pivotal connection about which the head may movetransversely of the record,

and means to restrain said head against movement about said pivot,comprising a resilient member attached to thehead, a friction pad on thecarriage, and means for urging said member into engagement with the pad.

5. In a stylus head mounting, acarriage arranged to move transversely ofthe record surface, means for'supporting the head on the carriageincluding a pivotal connection about which the head may movetransversely of the record, and means to secure said head againstmovement about said pivot, said means serving to'se'cure transversely of'the record surface, and a support on the carriage for the head,permitting universal movement ofthe head with respect to the carriage,said support comprising a pair of pivotal connections, the axes of saidconnections being normal with respect to each other.

9. In a stylus head structure adapted to operate optionally as arecorder head or as a reproducer head, a movable carriage upon which thehead is supported, means for providing lateral compliance for the headwith respect to the carriage, and means for optionally restraining thehead against lateral movement, comprising a pair of members respectivelycarried by the head and by the carriage and having cooperatingfrictional surfaces, said surfaces being capable of opera tiveengagement for any position of the head said head in a lateral positionas determined solely by the engagement of the stylus with the record. s

6. Astylus head for cooperation with a record, a carriage arranged formovement transversely of the record, said head being pivotally carriedby the carriage whereby the head may move independently of the carriage,a spring finger at tached to the head and arranged to affect themovement of the head. with respect to the carriage when flexed, andmeans for flexing said 1 finger, said means including a plungeron thecarrlage 'and electromagnetic means for moving said plunger. e

'1. Ina stylus head mounting, an arm to which the head is attached, apivotal support for the,

arm, said support being so arranged that the head can move toward oraway from the record surface, a leaf spring secured at one end on saidarm and extending in a generally radial direcv surfaces, one of saidmembers being resilient and capable of exerting a pressure on the headwhen the surfaces are in frictional engagement, and

' means to bring said surfaces into engagement.

11. In a stylus head structure adapted to operate optionally as arecorder head or as a reproducer head, a movable carriage'upon which thehead is supported, means for-providing latv eral compliance for the headwith respect to the carriage, and means for optionally restraining thehead against lateral movement, comprising a pair of members respectivelycarried by the head and by the carriage and having cooperatingfrictional surfaces, one of said membersbeing resilient and capable ofexerting a pressure on the head when the surfaces are in frictionalention from the arm with respect to said pivot, and

means for flexing said spring to cause it to exert a force urging saidarm about its pivot.

8. In a mounting for a stylus head, said stylus head being arranged forcooperation with a rec- 0rd surface, a carriage arranged for movementgagement, said surfaces being such as to permit operative engagement forany position of the head with respect to the carriage, within the limitsof movement permitted by said lateral compliance, and means to bringsaid surfaces into engagement.

FRANK RIEBER.

